1. Field of the Invention
The present invention relates generally to improvements in workpiece transport systems and, more particularly, pertains to apparatus for transferring workpieces into a sealed chamber containing reduced pressure in which an operation is performed on such workpiece.
2. Description of the Prior Art
Transport systems for inserting workpieces into a vacuum chamber insert the workpieces either singly or in batches through a door in the vacuum chamber. After the chamber is sealed, it must be evacuated to a vacuum. Then, the pressure must be increased again for removal of the finished workpieces and insertion of replacements.
In order to avoid this cumbersome process, the inventor of the present invention devised a method of transporting a plurality of workpieces through a sealed chamber on a continuous basis in a plurality of individual workpiece compartments which move along an input passage, into the sealed chamber, and then out of the chamber along an output passage. Each individual compartment is sealed while in the input and output passage so that pressure in the individual compartments can be independently varied as necessary. The pressure in the individual compartments is reduced before it reaches the sealed chamber, thereby avoiding wide fluctuations of the reduced pressure in the sealed chamber. This method avoids the cumbersome process of raising and lowering the pressure in the vacuum chamber every time a workpiece is inserted and removed.
This system, however, does not readily lend itself to an automated loading process for the vacuum chamber or manipulation of the workpiece while in the chamber as does the present invention.